Easy disagree from me. I could watch a movie like Das Boot if it was twice the already lengthy 4+ hours. Not to mention the 4-part Count of Monte Cristo among other more obvious ones like LOTR.
Movies you watch in theatres are one thing. It’s uncomfortable, you can’t pause it, you can’t contemplate it, there’s people all around you. It’s not an immersive experience despite a big screen.
So not all movies are best seen in a theatre. And the ones that aren’t are probably not long enough.